Department of Molecular Enzymology, Georg-August University Göttingen, Julia-Lermontowa-Weg 3, 37077 Göttingen, Germany.
Department of Structural Dynamics, Max-Planck-Institute for Biophysical Chemistry, Am Fassberg 11, 37077 Göttingen, Germany.
Biochemistry. 2020 Jul 21;59(28):2585-2591. doi: 10.1021/acs.biochem.0c00337. Epub 2020 Jun 29.
Amyloidogenic plaques are hallmarks of Alzheimer's disease (AD) and typically consist of high percentages of modified Aβ peptides bearing N-terminally cyclized glutamate residues. The human zinc(II) enzyme glutaminyl cyclase (QC) was shown in vivo to catalyze the cyclization of N-terminal glutamates of Aβ peptides in a pathophysiological side reaction establishing QC as a druggable target for therapeutic treatment of AD. Here, we report crystallographic snapshots of human QC catalysis acting on the neurohormone neurotensin that delineate the stereochemical course of catalysis and suggest that hydrazides could mimic the transition state of peptide cyclization and deamidation. This hypothesis is validated by a sparse-matrix inhibitor screening campaign that identifies hydrazides as the most potent metal-binding group compared to classic Zn binders. The structural basis of hydrazide inhibition is illuminated by X-ray structure analysis of human QC in complex with a hydrazide-bearing peptide inhibitor and reveals a pentacoordinated Zn complex. Our findings inform novel strategies in the design of potent and highly selective QC inhibitors by employing hydrazides as the metal-binding warhead.
淀粉样斑块是阿尔茨海默病（AD）的标志，通常由高比例的带有 N 端环化谷氨酸残基的修饰 Aβ 肽组成。体内研究表明，人类锌(II)酶谷氨酰胺环化酶（QC）可催化 Aβ 肽 N 端谷氨酸的环化，这是一种病理生理副反应，确立了 QC 作为 AD 治疗药物靶点的地位。在这里，我们报告了人类 QC 对神经肽神经降压素作用的晶体快照，描绘了催化的立体化学过程，并表明酰肼可以模拟肽环化和脱酰胺的过渡态。这一假设通过稀疏矩阵抑制剂筛选实验得到了验证，与经典的 Zn 结合物相比，酰肼是最有效的金属结合基团。通过与含有酰肼的肽抑制剂的人 QC 的 X 射线结构分析，阐明了酰肼抑制的结构基础，并揭示了一个五配位的 Zn 配合物。我们的发现为设计有效且高度选择性的 QC 抑制剂提供了新的策略，将酰肼作为金属结合弹头。
